The correct answer is A. deposit.
A deposit is a sum of money that is paid into a bank account. It can be made in cash, by check, or by electronic transfer. When you make a deposit, the money is added to your account balance. You can then use the money to make purchases, withdraw cash, or transfer it to another account.
A deficit is a shortfall in income or revenue. It can also refer to a negative balance in an account. A debit is an entry on a financial statement that decreases the balance of an account. A demote is to reduce someone in rank or position.
In the context of the question, the friend is taking his first pay to the bank to deposit it in his account. This means that he is adding money to his account. The other options do not make sense in the context of the question.